10 Homebuilt Tech Tools for the Developing World

Nearly 70 percent of the Earth may be covered in water, but try telling that to a landlocked farmer trying to eke out an existence in Africa. According to the Food and Agriculture Organization (FAO) of the United Nations, 1.6 billion people live in regions where water is extremely scarce. By 2025, two-thirds of the world's population -- nearly 4.5 billion people -- could face severe water shortages. One of the biggest issues is irrigation. Agriculture is responsible for 70 percent of all freshwater and groundwater withdrawals worldwide, says the FAO, and yet it's essential if rural farmers are to feed their communities. In fact, irrigating a farm can vastly increase the amount of food it produces.

Low-cost, human-operated pumps offer an ideal solution to this paradox. They enable small villages to get the water they need for drinking and irrigation without putting unnecessary stress on an area's water reserves. Over the years, farmers have experimented with many types of water-pump technologies, including rope pumps, treadle pumps and rower pumps. Many of these designs require some machining and welding experience, as well as access to sheet steel, valves and other components. That's what makes the EMAS-Flexi water pump such an attractive technology. Originally developed in Bolivia by the Mobile School for Water and Sanitation (EMAS, in Spanish) to serve extended families or small groups with no more than 50 people, the EMAS-Flexi pump uses readily available components -- PVC pipes, galvanized iron pipe, thread adapters and two glass marbles -- and can be assembled quickly and easily.

Here's how it works. One PVC pipe, slightly smaller, fits into a second pipe. At the bottom of each pipe, a glass marble acts as a valve. The inner pipe attaches to a metal T-shaped handle that is blind on one side and open on the other to form an outlet. The pumping movement raises and lowers the inner pipe, which moves within the stationary outer pipe. An upward stroke creates suction, drawing water into the cylinder. A downward stroke displaces water from the cylinder, forcing it out at the top. The operator can pump about 4 to 8 gallons (15 to 30 liters) of water per minute, which is enough to provide drinking water and irrigate a small garden.